Solar Panel

full_mosey wrote:

work2much wrote:

full_mosey wrote:
What happens if you blanket an entire panel in a series or parallel array?



HTH;
John

In parallel you will only kill the production of that panel. For 3 panels, one covered you will still have 2/3 production. In parallel each panel contributes separately. Think of three hoses filling a bucket vs series where the three hoses are connected together with a single discharge into the bucket at a higher psi. The flow is limited by the smallest diameter hose in series where in parallel each hose can fill at their own rate.

OK, using the hose analogy, if you have three hoses in series and you step on ANY location ALL current stops.

HTH;
John

Yes, that's essentially what you will see in the videos I posted and what I experienced myself testing both.Big drop in production. In full sun without shade series is better but not by much. In shade I had much better results with parallel. My results were pretty spot on with what the Wynns and Per found going through the same exercises in those videos.

work2much wrote:

full_mosey wrote:
What happens if you blanket an entire panel in a series or parallel array?



HTH;
John

In parallel you will only kill the production of that panel. For 3 panels, one covered you will still have 2/3 production. In parallel each panel contributes separately. Think of three hoses filling a bucket vs series where the three hoses are connected together with a single discharge into the bucket at a higher psi. The flow is limited by the smallest diameter hose in series where in parallel each hose can fill at their own rate.

OK, using the hose analogy, if you have three hoses in series and you step on ANY location ALL current stops.

HTH;
John

full_mosey wrote:
What happens if you blanket an entire panel in a series or parallel array?



HTH;
John

In parallel you will only kill the production of that panel. For 3 panels, one covered you will still have 2/3 production. In parallel each panel contributes separately. Think of three hoses filling a bucket vs series where the three hoses are connected together with a single discharge into the bucket at a higher psi. The flow is limited by the smallest diameter hose in series where in parallel each hose can fill at their own rate.

It's not what I saw on the internet. I went through the time and energy to do these tests myself. When you string three panels together in series you only pass the amperage of the weakest panel. That's not an opinion.

I guess we will will have to agree to disagree. Shade on a panel essentially makes it an unbalanced system as if one of the panels is 150 watts instead of 250. The basics can be found here of solar panels in series vs parallel where unequal panels provide different amperages.

https://solarpanelsvenue.com/mixing-solar-panels/

What happens if you blanket an entire panel in a series or parallel array?



HTH;
John

work2much wrote:
You are correct in that a diode will cut 20 cells or 1/3 of the panel. That panel now will be making 1/3 less amperage. Panels connected in series are limited by the production of the weakest panel so the entire string is now making 2/3 of its potential.

You are incorrect. The bypass diode act like a direct short and the Voltage across the diode goes to 0V and the diode passes all of the amps ie Now the 3 panels have 8/9 of the volts with full amps. ie 89% of the power of the 3 panels not 67%.

I get that your mind is made up based on whatever your saw on the internet. But I really don't want to continue and try to teach you basic electronics 101. So let's call it a draw.

CA Traveler wrote:

work2much wrote:

CA Traveler wrote:

devildog1971 wrote:
(for 4K I could have put 400 watts or more on the Bigfoot)

No doubt.

As a DIY I paid $1450 for 750W in 2014 for all of the parts including UV wires, aluminum for mounting and SS screws and bolts, etc. This included a high end Morningstar MPPT 60 controller. All panels in series which provides much better shade performance than parallel panels, but that is a whole different topic.

For shaded conditions parallel is superior. In series shading one one panel affects all the panels. In parallel it only affects the shaded panel.

I should have added that serial is superior when the panels have bypass diodes. Virtually all larger panels have bypass diodes. This may not apply to some 12V panels.

My 3 serial panels (90V total) have 3 bypass diodes each. Each diode will bypass 20 cells (10 volts) of my 60 cell panels when there is a shadow on that portion of the panel. So basically I have 9 serial panel sections. When 1 section has a shadow for example the diode causes a short which is 0 volts and passes the full amps of the other 8 sections. So the result is (90V-10V) * 8A (panel Imp) or 8/9 of the panels power.

The same panels in parallel result in 1/3 power loss, hence the voltage is lower than the other 2 panels. The result is the power is 6/9 of the 3 panels vs the serial 8/9 of the 3 panels.

In the past I've posted graphs showing the effect of bypass diodes. It's easy to see the 10V steps with full amps for the given sun condition on leafy shade, hard shade and other types of shade.

From past comments I'm aware that panel bypass diodes with serial panels and shade and not well understood. But with some electrical knowledge and research what I've posted can be verified.

You are correct in that a diode will cut 20 cells or 1/3 of the panel. That panel now will be making 1/3 less amperage. Panels connected in series are limited by the production of the weakest panel so the entire string is now making 2/3 of its potential.

Let's say your 250 watt panels are 30v @ 8.33 amps each. 750 watts total at 90volts@8.33 amps.

When 20 cells are bypassed that panel is only capable of 2/3 production or 5.5 amps. The other two panels will now be restricted to 5.5 amps as well. Maximum production will be 90v at 5.5 amps or 495 watts.

In a parallel configuration you would still have one panel dropping 1/3 power through the bypass diode. 5.5 amps now instead of 8.33. The other two panels would produce their full rated amperage of 8.33 giving a total of 8.33+ 8.33 + 5.5 or 22.6 amps at 30v or 665 watts. 170 watts more.

Wow, has this thread gone sideways or what? The OP resolved his problem 2 pages ago, it was a simple fuse.

Here is another side by side test series vs parallel. They tried 2 different panels both having bypass diodes.
https://www.youtube.com/watch?v=1qD3mN8VotQ

Here's an example of leafy shade on my panels and clearly shows the 10V increments as the shade is moving off of the panels. Battery amps are going up both due to less shade and increasing brightness of the sun.

https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/28956776.cfm